Split: File into multiple and keeping the same 3 lines from input into all output files

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The following code will split the infile into multiple files. However, I need it to insert the same first 3 lines from the original input file into each splitted file. How do I modify my script below to do so:
Code:
print -n "Enter file name to split? " ; read infile
if [ -z "$infile" ]
then
echo "Invalid file name entered ..."
exit 255
fi
print -n "Enter Number of files to split it into? " ; read numf
if echo $numf | egrep -q '^[2-9]{1}$'; then
echo
else
echo "Invalid number <$numf> entered. Entry must be numeric and 1 digits in length
(HowTos)

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